MAX771

19-0202; Rev 2; 11/96 L MANUA ION KIT HEET T A U L EVA TA S WS DA FOLLO 5V/12V/15V or Adjustable, High-Efficiency, Low IQ, Step-Up DC-DC Controllers ____________________________Features o 90% Efficiency for 10mA to 1A Load Currents o Up to 15W Output Power o 110µA Max Supply Current o 5µA Max Shutdown Current o 2V to 16.5V Input Range (MAX770/MAX771/MAX772) o Internal Shunt Regulator for High Input Voltages (MAX773) o Preset or Adjustable Output Voltages MAX770: 5V or Adjustable MAX771: 12V or Adjustable MAX772: 15V or Adjustable MAX773: 5V, 12V, 15V, or Adjustable o Current-Limited PFM Control Scheme o 300kHz Switching Frequency _______________General Description The MAX770–MAX773 step-up switching controllers provide 90% efficiency over a 10mA to 1A load. A unique current-limited pulse-frequency-modulation (PFM) control scheme gives these devices the benefits of pulse-width-modulation (PWM) converters (high efficiency at heavy loads), while using less than 110µA of supply current (vs. 2mA to 10mA for PWM converters). These ICs use tiny external components. Their high switching frequencies (up to 300kHz) allow surfacemount magnetics of 5mm height and 9mm diameter. The MAX770/MAX771/MAX772 accept input voltages from 2V to 16.5V. Output voltages are preset at 5V, (MAX770), 12V (MAX771), and 15V (MAX772); they can also be adjusted using two resistors. The MAX773 accepts inputs from 3V to 16.5V. For a wider input range, it features an internal shunt regulator that allows unli...